flash in the sky

[NikkiB]

A couple of months ago we were walking home in the early hours. The sky was perfectly clear, no clouds and all stars visible. There was a small flash in a part of the night sky. It can't have been lightning as there were no clouds. There was no sound either, nor sign of a shooting star. What could it have been? Some kind of stellar explosion millions of miles away?

[mibn2cweus]

I had a similar impression the first time I observed what was most likely an Iridium flare

This site heavens-above is helpful for predicting when and where you might observe a satellite or another flare.

[NikkiB]

Thanks for that site. I've just registered with them now!
However, it wasn't an iridium flare. It was a roundish flash, about the size of a fifty pence piece of sky if you held it around 3 inches from your face. It wasn't sharp edged or dazzlingly bright, more a sudden dull white or grey that quickly faded back to night sky.

[davenumber2]

A fireball

[mibn2cweus]

Something that large (bigger than the Moon) would almost have to be of atmospheric origins. The only apparitions I can imagine involving such a large area of the sky beyond the atmosphere is that from out-gassing of a comet which would persist for days.

The nearest star to the Sun is 250,000 times more distant and at the velocity of light would require days to swell to any apparent size if that were at all possible.

With the information you have so far provided my best guess is that you observed the vaporisation of a small comet upon impact with the Earth�s atmosphere?